Coupling graphitic carbon nitrides with tetracarboxyphenyl porphyrin molecules through π–π stacking for efficient photocatalysis

Abstract

Graphitic carbon nitride (g-C3N4) photocatalysts have attracted dramatically growing attention due to their attractive electronic structure, relatively low cost, high physicochemical stability, and earth-abundant features, but their practical applications are hindered by the fast recombination of photogenerated carriers, low conductivity, and lack of absorption towards longer wavelengths. In this work, a simple and effective strategy is demonstrated to highly promote the photocatalytic performance of the g-C3N4 by modifying with tetrakis (4-carboxyphenyl) porphyrin (TCPP) molecules, which can be tightly adsorbed on the g-C3N4 surfaces through π–π stacking. The typical TCPP/g-C3N4 photocatalyst with 0.1% TCPP content shows a highly enhanced photocatalytic degradation rate of 0.0591 min−1 towards Rhodamine B (RhB), which is more than two times higher than the 0.0224 min−1 for the pristine g-C3N4. Detailed investigations elucidate that the highly improved photocatalytic performance is contributed by the broadened visible light absorption and improved electron–hole separation efficiency and carrier migration efficiency induced by coupling TCPP molecules. Besides, RhB molecules prefer to be adsorbed on the TCPP/g-C3N4 surfaces, which is beneficial for the oxidative degradation reaction with the active species near the surfaces. This study may pave a new avenue to prepare highly efficient photocatalysts based on g-C3N4 by coupling conjugated molecules.